Which tropical forest conservation strategies are proving most effective?

A multitude of conservation strategies are currently deployed across the tropics in order to curb deforestation, preserve biodiversity, and mitigate global warming.

But conservationists and researchers often point to a need for more and better evaluations of the effectiveness of this diversity of conservation initiatives in order to determine what actually works and what doesn’t.

The latest assessment by the UN Food and Agriculture Organization found that Earth’s overall natural forest cover continues to shrink, though at a slower annual rate than in the past.

A multitude of conservation strategies are currently deployed across the tropics in order to curb deforestation, preserve biodiversity, and mitigate global warming. But conservationists and researchers often point to a need for more and better evaluations of the effectiveness of this diversity of conservation initiatives in order to determine what actually works and what doesn’t.

A collection of studies published by the journal PLOS ONE earlier this month seeks to fill this knowledge gap by evaluating the effectiveness of numerous tropical forest conservation policies and programs in Africa, Asia, and Latin America, including certification schemes, community-based forest management, forest law enforcement, payments for ecosystem services, and protected areas.

An overview study led by Jan Börner of Germany’s University of Bonn and the Center for International Forestry Research (CIFOR) focuses on annual forest cover change as a measure of the conservation effects estimated by the 14 studies in the collection. The latest assessment by the UN Food and Agriculture Organization found that Earth’s overall natural forest cover continues to shrink, though at a slower annual rate than in the past. “Reduced deforestation rates may be the result of slower economic growth, decreasing demand for cleared land in urbanizing economies, or a sign that conservation policies are succeeding,” Börner and his co-authors write in the overview study.

So which conservation strategies are actually proving effective on the ground in the tropics? Protected areas are, of course, one of the most frequently employed strategies, and four studies in the PLOS collection examined their effectiveness in Brazil, Chile, Costa Rica and Indonesia. Those studies found low to moderate positive effects, as protected areas in those countries were responsible for forest cover increases in the range of 0.08 to 0.59 percent per year.

“In the most effective protected areas (in this case the Brazilian Amazon), almost 6 percent more forest cover would be safeguarded in comparison to unprotected land in the span of just one decade,” according to a blog post by CIFOR that accompanied the release of the PLOS collection. “In the case of the least effective protected areas (in this case Indonesia), just 0.8 percent more forest cover would be preserved over a 10-year period.”

Börner and colleagues note in the overview study that “the global drop in rates of tropical tree cover loss is mostly driven by a few countries, such as Brazil,” which is perhaps why the country received more scrutiny than most. A study in the collection that looked specifically at protected areas in the Brazilian Amazon found that they reduced deforestation by two percent, on average, between 2000 and 2008. “However these impacts vary over space and time,” Börner and team write. “They find (1) lower effectiveness of protection as annual rates of forest loss went down in the region as a whole over time, and (2), higher effectiveness of protected areas located close to cities and transport ways, where pressure on forest resources tends to be high.”

Three more studies measured the effectiveness of other so-called “command-and-control” policies in Brazil that were among the array of measures that helped reduce Amazonian deforestation sharply over the past decade. (In 2012, the Brazilian Amazon experienced its lowest annual forest loss since satellite-based deforestation data first became available in 1989, and, despite a recent increase, the deforestation rate remains at historical lows to this day.)

Studies in the collection also examined incentive-based approaches like payments for ecosystem services (PES) schemes. A program in Costa Rica exhibited “intermediate forest conservation effects” of 0.32 percent per year, according to CIFOR, while a sub-national scheme in Mexico achieved a “strong” 2.91 percent annual forest area increase.

The long-term effects of PES were also evaluated. A study that looked at a sub-national payment scheme in Colombia, for instance, found that even after the program ended, its impacts were “almost entirely maintained.”

“Hence, where a previous meta-study had mostly found low environmental impacts from PES schemes, these new studies paint a somewhat more optimistic picture,” according to CIFOR. But the “overall largest forest conservation impact (4.56 percent annually) among incentive tools was measured when comparing forest cover changes between certified and non-certified timber concessions in Indonesia.”

The collection study that looked at Indonesian timber concessions certified by the Forest Stewardship Council determined that, between 2000 and 2008, certification increased forest cover by an average of five percent compared to non-certified concessions. “In addition, certification was associated with significant reductions in firewood dependence (33%), air pollution (31%), respiratory infections (32%), and malnutrition in participating villages,” Börner and his co-authors add.

Three further studies featured in the collection attempt to determine the socio-economic and development impacts of tropical forest conservation policies. One study found that PES in Costa Rica neither provided a boost nor proved to be a detriment to the welfare of local communities, whereas community-based forest management initiatives in Tanzania and Namibia provided significant health and educational benefits.

Ultimately, however, the authors of the overview study conclude that, because differences in the size of conservation impacts are not driven solely by the type of conservation measure employed, a key takeaway from the collected research is the need to move beyond the current scientific focus on estimating the average effects of “undifferentiated conservation programs” and instead to examine specific elements of each program and the context in which it’s being implemented — both of which “are equally important factors for understanding the effectiveness of conservation programs,” the authors write.

“Particularly critical will be a better understanding of the causal mechanisms through which conservation programs have impacts,” according to the authors. “To achieve this understanding we need advances in both theory and methods.”